A conversation with neuroscientist Lisa Feldman Barrett on the counterintuitive ways your mind processes reality—and why understanding that might help you feel a little less anxious.

BY CLAY SKIPPER  November 30, 2020  

Your Brain Doesn’t Work the Way You Think It Does

At the very beginning of her new book Seven and a Half Lessons About the Brain, psychology professor Lisa Feldman Barrett writes that each chapter will present “a few compelling scientific nuggets about your brain and considers what they might reveal about human nature.” Though it’s an accurate description of what follows, it dramatically undersells the degree to which each lesson will enlighten and unsettle you. It’s like lifting up the hood of a car to see an engine, except that the car is you and you find an engine that doesn’t work at all like you thought it did. 

For instance, consider the fourth lesson, You Brain Predicts (Almost) Everything You Do. “Neuroscientists like to say that your day-to-day experience is a carefully controlled hallucination, constrained by the world and your body but ultimately constructed by your brain,” writes Dr. Barrett, who is a University Distinguished Professor at Northeastern and who has research appointments at Harvard Medical School and Massachusetts General Hospital. “It’s an everyday kind of hallucination that creates all of your experiences and guides all your actions. It’s the normal way that your brain gives meaning to the sensory inputs from your body and from the world (called “sense data”), and you’re almost always unaware that it’s happening.”

People tend to feel like we’re reacting to what’s actually happening in the world. But what’s really happening is that your brain is drawing on your deep backlog of experience and memory, constructing what it believes to be your reality, cross-referencing it with incoming sense data from your heart, lungs, metabolism, immune system, as well as the surrounding world, and adjusting as needed. In other words, in a process that even Dr. Barrett admits “defies common sense,” you’re almost always acting on the predictions that your brain is making about what’s going to happen next, not reacting to experience as it unfolds. (Michael Pollan details the same neurological process in his book How to Change Your Mind.)

“Predictions transform flashes of light into the objects you see. They turn changes in air pressure into recognizable sounds, and traces of chemicals into smells and tastes. Predictions let you read the squiggles on this page and understand them as letters and words and ideas,” Barrett writes. “They’re also the reason why it feels unsatisfying when a sentence is missing its final.”

In her first book, How Emotions Are Made, Dr. Barrett cites research that suggests something similar happens with emotion. We experience things like anger or anxiety as feelings caused by outside events. But really, as Dr. Barrett says, “Emotions don’t happen to you—they are made by your brain as you need them.” That may sound like splitting hairs, but the consequences are quite profound: The more you know about emotions, the more precisely your brain can construct them, so you will feel and act in ways that are very specific to the situation. We talk a lot about “handling” emotions after they emerge (this is called emotion regulation), but understanding emotions as something you construct allows you to influence how they arise in the first place.

Of course, this upends notions of how we experience reality and leads to some interesting questions. Why does this happen? If we construct the reality around us, including our emotions, does that mean we can change how we feel? What should we do with the anxiety and stress brought on by coronavirus? If our actions are dependent on past experience, do we control what we do? How do we think about responsibility—say, in the renewed conversation around police violence—in a world like that? How can we use these seven and a half lessons to better exist in the world? GQ spoke to Dr. Barrett to ask these questions and more.

Lisa Feldman Barrett: The brain’s most important job is not thinking or seeing or feeling or doing any of the things that we think of as being important for being human. Its main job is running a budget for your body—to keep you alive, to keep you healthy. So every thought you have, every emotion you feel, every action you take is ultimately in the service of regulating your body. We don’t experience mental life this way, but this is what is happening under the hood.

The technical term for body budgeting is allostasis. It basically means that your brain’s job is to anticipate the needs of your body and meet those needs before they arrive. Budgeting resources like glucose, oxygen, salt, and all of the nutrients that your body needs so that you can do your most important job from an evolutionary standpoint: pass your genes on to the next generation.

There are limited resources [in your body] and every action that you take—every movement that you make, every new thing that you learn—costs something. And so every time your brain prepares to move your body or to learn something new, your brain is asking itself, figuratively, is this a good investment? Is it worth it?

This is one of the most amazing, and unsettling, revelations in the book, this idea that the brain is a prediction machine. Instead of passively observing reality—in what we think of as a stimulus-response pattern—it’s actually constructing our reality?

We can use a baseball example. The batter walks up to the plate. He takes his stance with the bat. A major league pitcher throws at a speed of 80 to 100 mph, giving the batter between 400 and 500 milliseconds to react. This is not enough time to see a ball, then decide to swing the bat, plan the action, and execute it. But a brain that works by prediction is fast enough to make baseball possible as a game.

Here’s what’s really happening: based on all the information that the batter has about the situation, his brain is automatically computing the swing, making a prediction about, in a moment’s time, where will the ball be. And so in the blink of an eye, his brain predicts the action, and then predicts his sensations. Figuratively speaking, his brain predicts: “What will I do in a moment from now? And the last time I acted this way in this situation, what did I see ? What will I feel in my joints? When the bat strikes the ball, what will I hear?” His brain is automatically changing the firing of its own neurons to anticipate the sensory changes that will result from the crack of the ball against the bat.

And so what happens? Information is coming in through his eyes and his ears and the rest of his sense organs. If the new information matches the prediction, then his motor response is completed, he swings the bat as planned and probably hits the ball. If there’s a difference, though, if his brain has not predicted something, say there’s a gust of wind or something happens with one of his tendons, then his brain may take in that new information and automatically adjust its prediction. But that adjustment will take long enough that he could miss the ball.

Predicting and correcting is a much more efficient way to run a system than reacting all the time. So what your brain is doing all the time is making these guesses, and then comparing them to sense data from your body and from the world that is continually arriving, as a way of reducing uncertainty, which, it turns out, is the metabolically efficient thing to do.

The example that got me in the book was the fact that it takes 20 minutes for water to reach your bloodstream, so when you drink a glass of water and feel like your thirst is immediately quenched, that’s not a biological reality, but a kind of a neurological trick.

Here’s another one that I just learned. You know how when it’s just starting to rain, and you might feel one drop of water on your skin, and you can tell it’s going to start to rain? Well, you have no wetness sensors in your skin. So how is it that you feel those drops of water? Your skin has touch sensors and temperature sensors, and your brain is doing this internal calculus……………………………………


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